FIG. 11 is a diagram illustrating an arrangement of a controller of a vehicle generator disclosed in, for example, Patent Document 1 (the Japanese Patent No. 4017637 Gazette).
The controller of the vehicle generator illustrated in FIG. 11 includes a three-phase armature winding 1, a rectifier 2 acting to rectify an AC output voltage of the armature winding 1 into DC, a field coil (inductive load) 3 to which a DC output voltage from the rectifier 2 is supplied to form a field circuit, and a voltage regulator 4.
Thus, the DC output voltage having been regulated at a constant value by the voltage regulator 4 is supplied to various electrical loads 5 as well as charges a battery 6.
A transistor 7 of the voltage regulator 4 is connected in series with the field coil 3 and functions as a switching element to control a field current to be carried through the field coil 3 by its ON/OFF operation.
To circulate an electric current of the field coil 3 at the time of OFF operation of the transistor 7, a diode 8 is connected in parallel with the filed coil 3.
Further, a detecting resistor 9 is connected in series with the transistor 7, and the detecting resistor 9 functions as field current detecting means acting to detect an electric current of the field circuit.
As described above, the conventional controller of a vehicle generator employs: a current detector of an inductive load that is provided with an inductive load (field coil 3); a switching element (transistor 7) connected in series with this inductive load and makes an ON/OFF control of an electric current of the inductive load; a current circulating diode (diode 8) connected in parallel with the inductive load and circulates an electric current of the inductive load at the time of OFF the switching element; and a detecting resistor 9 connected in series with the switching element and functions as field current detecting means acting to detect an electric current of the inductive load.
Patent Document 1: the Japanese Patent No. 40017637 Gazette